Electrical sound reproducer



July [12, 19 2. C W, BLACK v 1,866,921 I ELECTRICAL SOUND REPRODUCER 0 Filed May 27, 1929 3 Sheets-Sheet 1 y 12, c. w. BLACK ELECTRICAL SOUND REPRODUCER Fi-led May 27, 1929 '6 Sheets-Shrew- 2 July 12, 1,932. BLACK 1,866,921

ELECTRICAL SOUND REPRODUC ER Filed May 27, 1929 3 Sheets-Sheet 3 Patented July 12, 1932 PATENT OFFICE CORYDON W. BLACK, OF COUNCIL GROVE, KANSAS ELECTRICAL SOUND nErnoDUoEn Application filed May 27, 1929. Serial No. 366,422.

This invention relates to a reproducer adapted to convert electrical impulses into audible sounds and embodying an amplifying unit and an operating unit.

The invention has for one of its objects to provide a reproducer of the character stated which shall be capable of converting electrical impulses into perfectly natural and clear reproductions of the signals creating the impulses.

' The invention has for a further objectto provide a reproducer of the character stated wherein the operating unit shall embody an electromagnet adaptedto be connected to the output terminals of aradio receiving set, a telephone or other device for transmitting electrical impulses, an armature adapted to be connected to the amplifier, and tensioning and balancing means capable of supporting the armature in a manner to cause it practically to float in the air, in close proximity to the poles of the electromagnet, so that it will receive themagnetic impulses lfrom the poles of the magnet and respond thereto With such slight resistance, or bind, from said means, as to vibrate in perfect synchronism with them. y i The inventionhas'fora further object to provide a reproducer of the character stated net.

The invention has for a further object to provide a reproducer of the character stated wherein the operating unit shall include means through the medium of which one of the armature suspending cables may be twisted or turned to the end that the armature may be balanced to support it in exact proximity to each of the poles of the electromag- The invention has for a further object to i provide a reproducer of the character stated wherein the tensioning and balancing means, whilepermitting great freedom of piston-like vibration of the'armature directly toward and directly away from the electromagnet, shallbe cable of so perfectly supporting the armature and restraining it from any lateral movement as to make quite practical theentire support of an amplifying cone, diaphragm or the like by the armature.

The invention has for a further object to i provide areproducer of the character stated wherein the amplifying unit shall be provided with a main baflle board, a sub-bafile 30 board, and a resonance release.

The invention has for a still further object to provide a reproducer of the character stated wherein the sub-baflle board and resonance release shall be adjustable.

With the foregoing and other objects in view, the nature of which'will appear as the description proceeds, the invention consists in the construction, combination and arrangement of parts hereinafter fully described and claimed and illustrated in the accompanying drawings, wherein a scale of the operating unit of the reproducer;

Figure 3 is a sectional view taken on the vertical plane indicated by the line 33 of Figure 2; i

a Figure 4: is a sectional View taken on the vertical plane indicated by the line 4-4 of Figure 2;

Figure 5 is a perspective view of one of the pole pieces of the operating unit;

Figure 6 is a sectional view taken on the vertical plane indicated by line 66 of Figure 2;

Figure 7 is a sectional view taken on the vertical plane indicated by the line 77 of Figure 1; i

a Figure 8 isa sectional VIEW illustrating a slight modification in the manner of securing the amplifying device to the armature of the operating unit; and i a Figure 9 is a sectional viewillustrating a slightly modified arrangement of the driving or operating unit, amplifying device and air chamber. a l y The driving or operating unit of thereproducer comprises a permanent magnet 1 of the closed or endless type. While the magnet 1 is shown as beingof elongated formation in plan,.it may be of any other desired formation. A positive pole piece 2 and a negative pole piece 3, of bifurcated or U-form, are arrangedwithin the magnet 1. The pole pieces 2 and 3 are arranged in op posed relation transversely of the magnet 1. The pole piece 2 is secured through the medium. of its outer prong or flange 2 to the side 1" of the magnet 1, and the pole piece 3 is secured through the medium of its outer prong or flange 3 to the side 1 of the magnet. I The inner prong or flange 2 of the pole piece 2, and the inner prong or flange 3 of the pole piece 3, have arranged thereon coils 4t and 5, respectively, to provide an electromagnet, which is in practice connected to the outputterminals of a radio receiving set, a telephone or other device for transmitting electrical impulses, and is provided with an armature 6. i a

The armature 6. has secured thereto an actuating rod 7 for an amplifying device. The armature 6 is suspended above the electromagnetic pole tips 2 and 3 and the rod 7 extends upwardly from the armature. The head 7 of the rod 7 iscountersunk in the armature 6. The armature 6 and the rod 7 are secured together by a nut 8 mounted upon the rod and a clamp 9 mounted upon the ner ends to the pole pieces by bars 12 secured to the pole, pieces by screws 13. Levers 14: are arranged at opposite sides of the electromagnet and overlie the arms 11, and are rockably supported at their inner ends upon the bars 12 by fulcrum blocks 15. The outer ends of the levers 14; are supported from the corresponding ends of the arms 11 by bolts 16.

Nuts 17 mounted upon the bolts 16 and contactingwith the upper and lower sides of the arms 11, serve to fixedly secure the bolts to the arms.

M Nuts 18 adj ustably mounted upon the bolts 16 and contacting with the upper and lower sides ofthe levers 14, provide means through the medium of which the levers. may be adjusted or'rocked upwardly and downwardly on'their fulcrum blocks 15, and throughthe medium of which the levers are secured in their adjusted position. The levers 14 are provided at their outer ends with upstanding cars 19 wlth whlch are rotatably ZLSSOClfif'DGd nuts 20. The nuts 20 ar-eaxially alined and their axes are arranged parallel to the longitudinal center of the electromagnets. The

nuts 20 contact with the outer sides of the ears 19, and are provided with knurled operating flanges 20 A flexible suspending cable 21 for the armature 6 extends across the longitudinal center of the electromagnets and passes through the openings 10 in the rod 7 and.

clamp 9. The cable 21 is of angular formation in cross section and has a snug fit in the 'openlngs lOso as to prevent the armature 6 and cable from having any relative rocking or turning movement. The nut 8 and the clamp 9 serve to bind the armature 6 against or downwardly through the medium of the nuts 18, the position of the armature 6 above theelectromagnetic pole tips 2 and 3 may be varied to effect the increasing or lessening of the air gap, as a whole, between the pole tips and the armature.

I As the nuts 20 contact with theouter sides ofthe ears 19, and as the ends 21 of thecable 21 are threadedly engaged with the nuts, the

tension ofthe cable may be varied by turn ing the nuts. The cable 21 is maintained under tension by lock nuts 22 mounted upon the screw threaded ends 21 of the cable 21 and contacting with the inner sides of the ears 19. The cable 21 is supported at oppositesides of and relatively close tothe armature 6 by brackets 23 which aresecured to the inner ends of the levers 14 by bolts'2 l. The brackets 23 each comprises a base 25, a cap 26 and a pivot 27 arranged between the base and cap. The parts of the. respective brackets are'secured in assembled relation 1 axial bores of angular formation for the snug reception of the cable 21. -The pivot sections 27 are each provided with a circular flange 28, and an arm 29 extends radially from each flange. The arms 29 are connected to the levers 14 by bolts 30, which are fixed to the levers by their heads 30 and nuts 31. Nuts 32 adjustably mounted upon the bolts 30 and contacting with opposite sides of the arms 29 provide means through the medium of which the'arms may be rocked to eflect the angular adjustment of the pivots 27. The nuts 2% of the bolts-24l are loosened to permit the adjustment of the pivots 27 and are tightened after the adjustment of the pivots. To permit the brackets 23 to be adjustedin the direction of and awayfrom the armature 6, the levers 14 are provided with longitudinally extending slots 33 and 34 for the reception of the bolts 24 and 30, respectively. The slots 33 and 34 are parallel to i the axis of the cable 21 so as to permit the 21, and this movement of .the cable imparts a corresponding rocking movement to the armature 6. It will thus be seen that the brackets 23 providemeans through the medium of which the armature 6 may be balanced to support it in exact proximity to each of the positive and negative electromagnetic pole tips 2" and 3'. It willralso be seen that the adjustability of the brackets 23 with respect to thearmature 6. permits the distance between the points of suspension of the cable'2'1 to beincreased or decreased. r i

Arms 35, arrangedat opposite sides oft-he pole pieces 2 and3 in a plane right angularly related to the plane of the arms 11,are secured to the outersurfaces of the sides l -and 1? of the magnet 1. The arms 35 extendlup wardly and outwardlvfrom the magnet 1, and are provided at their upper ends with upstanding ears 36. A flexible cross cable 37 is connected at. its ends to the ears The ends of the cable 37 are screw threaded for the reception of attaching nuts 38 which contact with the outer sides of the ears 36 and are provided with knurled operating flanges 38. Lock nuts 39 are mounted upon the ends 7 of the cable 37 and contact with'the-inner sides of the ears 36.. The cable 37 is provided intermediate its endswith aflattened portion 37 a through which the armaturerod 7 passes and to'which said rod is secured by nuts 40 arranged upon the rod and contacting with the upper and lower sides. of said cable portion. The cable 37, which is arranged approximately at right angles to the cable 21, serves. in connection with the cable 21, to suspend the armature 6 in the air gap and to maintain a practically perfect floating relation between the armature and the electromagnetic pole tips2 and3P. i The nuts 38 provide means which permits the tension of the cable 37 to be adjusted so as to support and hold the armature 6 in exact relation to each of the positive and negative electromagnetic pole tips 2 and 3,

it being understood that such relationbetween the armature and the poletips is obtained through the medium of the pivots 27, which aremounted for rotation orangular adjustment with respect to the axisof the cable 21. After the cable 37 has been adjusted to the requiredfltensiomthe lock nuts 39 are tightened to hold it under'such tension.

It should be understood that the armature 6 is suspended in the air gap and maintained in practically perfect relation with respect to the electromagnetic pole tips 2 and 3 with theresult that the armature 6 and actuating rod 7 are permitted great freedom of pistonlike vibration directly toward and directly away from the electromagnetic pole tips 2 and 3". The armature-6 and actuating rod 7 i are so perfectly supported and restrained from any lateral movement as to make quite practical the entire support of the amplifying cone, diaphragm or other sound amplifying deviceby the actuating rod.

- The resonator or amplifying device 41 may be secured to the actuating rod 7 in any suitable manner. As shownin Figures 1, 3 and 4,

the amplifying device41 may be secured to the actuating rod 7 by nuts 42 engaged with the rod'and contacting with the upper and lower sides of the ferrule 43 of the amplifying de' vice. As shown in Figure 8, the amplifying device .41 may be secured to the actuating rod 7 by one of the nuts 40 and a nut 44 which contact with the opposite sides of the ferrule 43. i

p The pole pieces 2 and3 may each be made of one solid piece of metal of good magnetic conductivity, or they may each be made of laminated sections for a purpose well known tothose skilledin the art. Thearmature 6 may be made of one solid piece of metal of good magnetic conductivity, or it may be made of laminated sections. In the event that the armature 6 is to be of laminated construction, it is preferable to have each of the lami-. nated sections thereof correspond toand register with a laminated section of the electromagnetic pole pieces 2 and 3 The arm attaching bars :12 are made of non'kmagnetic material, and it .is preferred that the arms 11, levers 14, fulcrum blocks-15, brackets 23 and arms 35 be also. made of the same materia a The driving or operating unit, substantially in the form described, may be mounted in a small wooden, fiber or metalcase with the outer edge or periphery of the amplifying device 41 entirely free from any contact with the case or with its. periphery attached flexibly to the case. While excellent results are attainable fromthis arrangement, the results would be greatly enhanced by using. the drivingor operating unit in a cabinet with asufiicient-baflie, or additional exponential airchamber or a combination of both bafile and exponential airjchamber, and especially so when a resonance or air pressure release is provided, and this resonance release isin net, 46 a main baffle board, 47 a sub-baffle I board,48 an air chamber and 49 an air escape gradually away from the main baflie board 46. In this particular embodiment, the air escape ring 49 is attached to the main baffle board 46, which is really the beginning of the amplifying air chamber 48, the lateral walls of such chamber enlarging exponential ly to its mouth.

. The air escape ring 49, with its attached sub-baiiie board 47 is secured to the main bafie board 46 and amplifying air chamber 48 by screws 51 in a manner to provide a very slightopemng or passage 52 between the air escape ring and the main battle board. The

width of the air escape opening or passage 52 may be lessened by turning the screws 51 in a clockwise direction and increased by turning the screws in a counter-clockwise direction. Coil springs 53 are arranged upon the screws51 between the main baflie board Miami the air escape ring 49, and normally tend to push the air escape ring away from the main baffle board, whereby to insure the movement of the air escape ring into the desiredposition with respect to the main battle board when adjusting the screws in a counterclockwise direction to effect the enlargement of the air escape opening or passage 52. If desired, straight springs, not shown, may be used inplace of the coil springs 53.

The amount of air vibration allowed to escape through the opening or passage 52 is just suiiicient to reduce the noise'level to its possible minimum, as is well under stood in the art. This released air vibration is prevented from coming into immediate contact with the air vibration back of the cone 41 by the sub-baffle board 47 whereby to eliminate the discord or noise that would be instant to such immediate contact.

If desired, the driving or operating unit and the cone 41 may be secured to the exponential amplifying air chamber, with the unit and cone arranged within the chamber and in inverted position, as shown in Figure '9. If desired, the exponential air chamber maybe omitted. and in this case the opening in the main baflie board would serve as the mouth of the device. H r V The mouth of the air chamber 48 may be covered by a grill 53 or by silk or other light fabric, and the opening in the opposite side of the cabinet 45 maybe provided witha light fabric covering 54. The driving unit maybe securely attached to the main baffle board 46 and air chamber 48 by suitable brackets which are not shown as they form no part of this invention. i V a While much better results will be attained by using the driving or operating unit shown and described herein in combination with the main baffle board 46, it is to be understoodthat another type of driving or operating unit may be used when so desired and it is also to be understood that when desired, another type of baffle and amplification may be used with the driving unit shown herein. The highly tensioned cables or wires, due to their arrangement at approximate right angles to each other and to theirconnection at offset points on the vibrating element, which element includes the armature, strut or rod and resonator, support said element rigidly as against any lateralmovement and allow al- 7 most perfect freedom of piston-like vibration thereof directly toward and directly away from the magnetic pole tips. The construction of the vibrating element support, and the manner in which it is secured to said element, causes said elementto respond with'greater freedom and'fidelity to actuation by its magnet than is possible with either the more massive andstiffer structural constructions or y when it is necessary to separately support the resonator. The delicacy of the vibrating element support and the restorative quality of said support causes the vibrating element to respond precisely to each and every overtone, the colorful beauty of which in each voice and instrument lends the delightful charm to harmony.

While I have described the principle of the invention together with the structure which I now consider the preferred embodiment thereof, it is to beunderstood that the structure shown is merely illustrative and that such changes may be made, when desired,.as

-of force to actuate the armature, and, tensioned flexible members supportingthe arma ture and connected respectively thereto and to the rod at relatively spaced points.

3. Anelectromagnetic device, comprising an armature provided with aconnecting rod,

means for creating variable magnetic lines of force to actuate the armature, and tensioned flexible members supporting the armature 6&

and connectedrespectivelythereto and to the rod at relatively spaced points and arranged at substantially right angles to each other. 4.A n electromagneticdevice, comprising an armature, means for creating variable magnetic lines of forceto actuate the armature, tensioned flexible members arranged atsubstantially rightangles to each other,

means rigidly securing the armature to said means rigidly securing the armature to'said members, means by which the tension ofeach of saidmembers may be varied, and'means bywhich one of said members may be turned about its axis. t i v v 6. An electromagnetic device, comprising anarmature means for creating variable magnetic lines of force to actuate the armature, a tensioned flexiblemember for supporting the armature for actuation toward and away from said means, arms extending in opposite directions from said means and rockablymounted at their inner ends and having said member connected to their outer ends, andmeans for rocking the arms toeffect an adjustmentof thearmature with respect to its actuating means and for securing the arms against accidental movement.

7. An electromagnetic device, comprising an armature, means for creating variable magnetic lines of force to actuate the armature, a tensioned flexible member extending across said means, means securing the armature to said member against any relative movement with respect thereto, arms extend ing in opposite directions from said means and rockably supported at their inner ends and having said member secured to their outer ends, means for rocking the armsto effect an adjustment of the armature Wlth respect to its actuating means and for securing the arms against accidental movement, and means carried by the arms and adapted to permit said member to be adjusted about its axis. a v

8. An amplifying device, comprising an air chamber, a main baflle board, a sub-baflle board, means adjustably'holding the bafile boards in their relatively spaced relation, an amplifying member connected flexibly atits periphery to the sub-baffle board, and electromagnetic means for actuating said memher.

9. An electromagnetic device, comprising an armature, means for creating var able magnetic lines of force to actuate the armature, fiexible members arranged at substan tially right angles toeach other,means terminally supporting said members, means rigidly connecting saidmembers to-the armature, and means for supporting one of said members at points between the ends thereof and at opposite sides of the armature.

10. An electromagnetic device, comprising an armature, means for creating variable magnetic lines'of force to actuate the arma-v ture, flexible members arranged at substantially right angles to eachother, means terminally supporting said members, means rigidly connecting said members to the armature, andmeans for supporting one of said member-sat points between its ends and at opposite sides of the armature and adjustable toward and away from the armature.

11. An electromagnetic device, comprising an armature, means for creating variable magnetic lines of force to actuate the armature, tensioned flexible members secured bea tween their ends to the armature, means to which said members are terminally connected, and meanssupportmg one of said members at points between the ends thereof and i at opposite sides of thearmature and adj ustable toward and away from the armature.

12. An electromagnetic device comprising anarmature provided with a connecting rod, means for creating variable magnetic lines of force to actuate the armature, a tensioned flexible member secured between its'ends to positedirections from said first means and rockably mounted at their inner ends and having said second flexible member terminally secured thereto outwardly beyond the inner ends thereoifland means carried by said arms for adjustment thereon towards and away from said opposite sidesof the armature, said second flexible member connected to said last means and supported thereby between its ends and at opposite sides of the armature. V

13. An electromagnetic device, comprisin an armature provided with a connecting rod, means for creating variable magnetic lines of force to actuate the armature, a tensioned flexible member secured between itsends to the connecting rod at a point spaced from the armature, means to which said flexible member isterminally secured, a second tensioned flexible member secured between its ends to ,the armature, arms extending in opposite directions from said first means and rockably mounted at their inner ends and havlng said second flexible member terminally secured thereto outwardly beyond the inner ends thereof, and means carried by the arms for a adjustment thereon-towards and away from said opposite sides of the armature, said second flexible member c'onnectedjtosaid last means and supported thereby between its Comprising an armature provided With a connecting rod-, means for creating variable magnetlc lmesof force to actuate thearmature, axially tQIlSlOIlG'Cl flexible members connected respectively to the armature and to the rod at relatively spaced points and sup porting the armature and rod for movement in the direction ofthe axis of said means, and an amplifying member secured to and solely supported by the rod.

15. An acoustical "device, comprising an amplifying member, a battle board, an airescape ring, means for holding the baffle board and ring in relatively spaced relation,

andelectromagnetic means for actuating the amplifying member.

16. An electromagnetic device, comprising an armature, a connecting rod extending axially from the armature, means for creating variable magnetic lines of force to actuate the armature, a flexible member secured between its ends to the armature, means supporting the flexible member near opposite sides of the armature and providing adjustment of the position of said supporting means in relation to the armature, and also providingadjustment of the position. of the armature in relation to the electromagnetic poles, means for maintaining the flexible member under axial tension, and a second tensioned flexible member supportedat approximate right angles to said first flexible member and attached to the connecting rod at an offset point in line with the axis of the armature. I p

17. An electromagnetic device, comprising lines of force to actuate the armature, axially tensioned flexiblemembers arranged at substantially right angles to each other and connected respectively to the armature and to the connecting rod at relatively spaced points,"

the flexible members supporting the armature and the connecting rod for movement in the direction of the axis of said means andretuated position, and means for adjusting the axial tension of the flexible members.

20. An electromagnetic device, comprising storing the armature to its normal or non-acan armature having aconnecting rod secured thereto, means for creating variable magnetic lines of force to actuate the armature, axially tensioned flexible members," arrangedx sub-* stantially at right angles to each other and connected respectively to" the armature andto V oonrnon W, BLACK,

- an armature having a connecting'rod secured V thereto, means for creating variable magnetic lines of force to actuate the armature, and axially tensioned flexible members arranged at substantially right angles to each other and connected respectively to the armature'andto the connecting rod at relatively spaced points andsupporting the armature and the connecting rod for movement in the direction of the axis of said means.

18. An electromagnetic device, comprismg an armature having a connecting rod secured thereto, means for creating variable magnetic lines of force to actuate the armature, axially tensloned flexible members arranged at sub-V stantially right angles to each other and connected respectively to the armature and to the connecting rod at relatively spaced points and supporting the armature and the connecting rod for movement in the direction of the axis of said means, and means for adjusting the axial tension of the flexible members.

19. An electromagnetic device, comprising 7 anarrnature having a connecting rod secured 'theret'o,means for creating variable magnetic 

